QUESTION 2 The following feed mixture is to be separated by ordinary distillation at 120 psia to obtained 92.5 mol% of n-C4 in the liquid distillate and 82 mol % of the i-C5 in the bottoms. The relative volatility (a) values are given in Table 1. The a can be assumed to remain constant within any variation in temperature. 2.1. 2.2. 2.3. 2.4. Table 2: The average relative volatility (a) Component C3 i-C4 n-C4 i-C5 n-C5 Mole fraction 0.25 0.35 0.15 0.05 0.20 4.36 2.36 1.88 1 0.84 Determine the light key (LK) and heavy key (HK). Use Underwood's method to determine the minimum reflux ratio (Rmin). (Use 0 = 1.02, (2) 1.07, 1.1 as estimate values). (16) Use the Fenske equation to calculate the minimum number of stages required, assuming feed is at the bubble point. (5) Use the Gilliland correlation to calculate the final number of stages, if R=1.5Rmin. (9) [32 marks]